Every built-in project, in one grid

A pushbutton and a 2 Hz clock, no processor in sight.

A switch, a resistor and an LED: the first circuit, with the whole loop in view.

A 2N7000 switching an LED from a slide switch, with no gate resistor anywhere: the switch a board pin reaches for.

One switch drives an IRF520 module and a D4184 module, each on a 12 V load: the IRF520 is half on from 5 V and off from 3.3 V.

A 1N4733A holding 5 V out of a 12 V supply, with the load line that says where it settles and what the load costs.

An LM317 on a 12 V adapter with 240 ohms and a 2 k pot: Vout = 1.25 V x (1 + R2/R1), from 1.25 V up to the dropout, with an LED on the output.

A 12 V adapter into an LM2596 buck module set to 5 V, its output on the Uno 5V pin, and A0 reading the adapter through a 10k and 4.7k divider.

A USB-C breakout on a computer port feeds an AP2112K-3.3 low dropout regulator, which lights an LED at 3.3 V.

An 18650 cell into an MT3608 boost module set to 12 V lights a 12 V lamp, and keeps it lit at 12 V as the cell runs down.

A 230 V to 12-0-12 V mains transformer, two 1N4007s as a full-wave rectifier and 1000 uF of smoothing: a scope shows the ripple and a meter the DC into a 100 ohm load.

A TCS3200 color sensor with two slide switches picking its red, green, blue or clear filter and a frequency counter on OUT: the more of that color, the higher the frequency.

Two 12 V sources make a split supply, and a 7805 and a 7905 turn it into +5 V and -5 V, each with a load on it.

A 555 astable drives a piezo straight from the output pin, no board and no button.

Two buttons drive an AND, an XOR and a NOT, so the truth table lights up as you press.

A clock, two D flip-flops and a multiplexer on three LEDs: a toggle, a one-tick delay, and set and reset on buttons.

Two 74HC74s ripple-count on four LEDs, four steps a second, no microcontroller.

A 555 astable clocks a CD4017 decade counter and ten LEDs take turns to light, with no microcontroller.

A 74HC165 loads an 8-way DIP switch at the press of a button and clocks the byte out one bit a second onto an LED.

Four DIP switches set a number in binary and a CD4511 shows it as a digit on a seven-segment display.

A 74HC14 oscillator clocks a 74HC161 counter and a 74HC138 decoder lights one LED of eight at a time.

A slide switch and a 74HC02 steer a clock into a 74HC193, which counts up or down in binary on four LEDs.

Two JK flip-flops in a 74HC112 toggle on each falling clock edge and count 0 to 3 in binary on two LEDs.

A CD4060 oscillates on two resistors and a capacitor and divides it down to blink four LEDs, each at half the rate of the one before.

A CD4026 counts clock pulses and drives a seven-segment display itself, 0 to 9 and round again.